USH1979H1 - Electronic streak camera - Google Patents
Electronic streak camera Download PDFInfo
- Publication number
- USH1979H1 USH1979H1 US09/148,910 US14891098A USH1979H US H1979 H1 USH1979 H1 US H1979H1 US 14891098 A US14891098 A US 14891098A US H1979 H USH1979 H US H1979H
- Authority
- US
- United States
- Prior art keywords
- radiation
- streak camera
- lens
- optical
- collimating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000005855 radiation Effects 0.000 claims abstract description 21
- 230000003287 optical effect Effects 0.000 claims abstract description 20
- 238000001228 spectrum Methods 0.000 claims abstract description 8
- 238000003384 imaging method Methods 0.000 claims abstract description 6
- 239000000463 material Substances 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
- 230000003595 spectral effect Effects 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 238000004616 Pyrometry Methods 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- ILVUABTVETXVMV-UHFFFAOYSA-N hydron;bromide;iodide Chemical compound Br.I ILVUABTVETXVMV-UHFFFAOYSA-N 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000009290 primary effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 210000001747 pupil Anatomy 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature
- G01J5/601—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature using spectral scanning
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
An electronic streak camera is described which includes a housing enclosing an objective lens disposed along an optical axis for forming an image of optical radiation from an emissive body, a pinhole field stop at the focal point of the objective lens, a collimating lens for collimating radiation passing the pinhole field stop, a prism for splitting the radiation from the collimating lens into a characteristic optical spectrum of the radiation, an imaging lens for forming an image of the radiation from the prism.
Description
The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
The present invention relates generally to electronic streak camera structures, and more particularly to an electronic streak camera structure having no moving parts for accurate imaging of high speed transient events.
Conventional streak camera systems for measuring temperature of energetic environments have been substantially dominated by system noise, the primary effect of which is that energy gathered for in each measured wavelength is somewhat higher or lower than true readings. In a conventional streak camera, a mirror is rotated in the pupil of the optical system to separate time events onto a fixed focal plane. A prism or diffraction grating is typically used to disperse the optical energy onto a detector. Mechanical jitter of the rotating mirror inherently introduces error into the measurements. Additionally, conventional streak cameras are light-inefficient and are typically ten stops lower than a standard electronic camera, reducing the amount of light collected by a factor of 100 or more. To amplify the light, photomultiplier tubes or multi-channel plates are used, which introduce substantial additional noise. Only general radiative characteristics can be obtained with these systems because of the limited signal-to-noise performance.
The invention solves or substantially reduces in critical importance problems with conventional streak camera structures by providing a streak camera including a spectrometer having no moving parts for use in recording high speed transient events. The camera of the invention is characterized by low noise and low cost of operation, provides improved light efficiency (two orders of magnitude) and greater light collecting capability (f/2 vs f/20) compared to conventional streak camera structures, and permits temperature determinations accurately for highly dynamic test events such as internal combustion in engines, materials deformation in hot metal processing and detonating or deflagrating explosives, including measurements at very high rates of temperature change (hundreds of degrees per millisecond).
For the purpose of describing the invention and defining the scope thereof, the term “optical” shall, in accord with customary usage, be defined herein to include only ultraviolet, visible, near infrared, mid-infrared and far infrared regions of the electromagnetic spectrum lying between about 0.1 to about 1000 microns (see, e.g., Optical Physics, Max Garbuny, Academic Press, NY, 1965, pp 1-6), and more specifically to the range of from about 0.2 micron, the approximate lower limit of operation of fine quality quartz lenses (Garbuny, p 280), to about 50 microns, the approximate upper limit of operation of long wavelength transmitting material such as thallium bromide-iodide ionic crystal (Garbuny, p 282).
It is therefore a principal object of the invention to provide an electronic streak camera.
It is another object of the invention to provide an electronic streak camera for use in high-speed pyrometry of energetic materials.
It is a further object of the invention to provide an electronic streak camera having no moving parts.
It is a further object of the invention to provide an electronic streak camera for acquiring temperature data on explosive materials.
It is yet another object of the invention to provide an electronic streak camera for acquiring temperature data at high rates of temperature change.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.
In accordance with foregoing principles and object of the invention, an electronic streak camera is described which includes a housing enclosing an objective lens disposed along an optical axis for forming an image of optical radiation from an emissive body, a pinhole field stop at the focal point of the objective lens, a collimating lens for collimating radiation passing the pinhole field stop, a prism for splitting the radiation from the collimating lens into a characteristic optical spectrum of the radiation, an imaging lens for forming an image of the radiation from the prism.
The invention will be more clearly understood from the following detailed description of representative embodiments thereof read in conjunction with the accompanying schematic drawing illustrating a representative electronic streak camera structure according to the invention.
Referring now to the drawing, shown therein is a schematic illustration of a representative electronic streak camera 10 structure of the invention. Objective lens 11 is disposed within an opening in a wall of housing 12, lens 11 being selected in size and focal length for forming an image of radiation 13 passing along optical axis O from an emissive body 14 onto pinhole field stop 15 disposed within housing 12 substantially as shown in the drawing. Radiation passing through pinhole 15 is collimated by lens 17 and split into its characteristic spectrum 19 by prism 20. Lens 21 then images spectrum 19 onto detector array 23 disposed at the focal plane of lens 21. Housing 10 may be of any suitable structure for enclosing camera 10 constituent elements. Detector array 23 may comprise any suitable detector system such as a CCD array or other charge transfer detector system, the same not considered limiting of the invention. Scanning is achieved by clocking the line image of the array to the adjacent row, which no optical energy from the object reaches.
Using the formula for the characteristic radiation of a material (usually a Planck distribution) total radiation from the material can be found by multiplying this formula by the surface emissivity. Multiple spectral measurements can be used to determine temperature when the radiation formula is a function of temperature and wavelength. However, using a camera to collect the spectrum has often been based on assumptions that lead to erroneous results, primarily because of the uncertainty in the collected optical energy. Emissivity, atmospheric transmission, detector non-linearity, etc. can all affect the amount of energy collected, depending on wavelength and bandwidth at which the measurement is made. The problem may be reduced to an uncertainty in emissivity (see e.g., Methods of Optical Polychromatic Pyrometry, V. N. Snopko, Plenum Publishing Co. (1988) pp 724-729). Emissivity can be characterized with an Mth degree polynomial in wavelength by
where the constants describe emissivity behavior. If, for example, a material has an emissivity that does not change with wavelength (graybody), only a1 need be determined because all other constants are zero. Consequently, only two spectral measurements are necessary to form two equations for the two unknowns (a1 and temperature T). If an Mth degree polynomial provides an accurate fit to a given material emissivity profile, there will be M coefficients, aM+1 . . .a2, of wavelength that will be unknown. With a1 and T unknown, a minimum of M+2 spectral measurements are required.
where n is the number of spectral regions, c the velocity of light, h is Planck's constant, k the Boltzmann constant, τa(λ) the transmission of the atmosphere, τo(λ) the transmission of the optics, Rd(λ) the responsivity of the detector and A0 the area of the optics. Solving Eqs (2) will separate the coupled response of temperature and emissivity.
System parameters such as detector response and solid angle are known quantities after system calibration and can be represented as a single function Ri(λ). Transmission terms of Eq (2) can be folded into Ri(λ) for simplicity. The power on the detector Eq (2) can be rewritten as
The system of equations generated from the multi-spectral measurements is nonlinear because of terms associated with the Planck distribution, and a nonlinear regression optimization technique is therefore required. The equations can be made linear by holding temperature constant and obtaining a solution and an error function establishing accuracy of the predicted temperature. A regression through temperature gives the correct temperature at the minimum error function. It is important therefore to represent the emissivity as a linear function. For purposes of the linear solution technique, emissivity will be assumed to fit a second order polynomial functional form.
The linear solution technique uses Gaussian elimination to find a solution to the system of four equations constructed from four spectral measurements. With a second degree polynomial as the model for emissivity, the four equation setup by the four color pyrometer are:
Each of the integrals of Eq (6) can be evaluated,
Using Gaussian elimination, the coefficients can be determined and substituted into the fourth equation. If there is no error in Eq (9), the assumed temperature was correct, otherwise the temperature assumption needs to be changed and the coefficients recomputed.
The teachings of all references cited herein are hereby incorporated by reference herein.
The invention therefore provides an electronic streak camera having no moving parts for the accurate imaging of high-speed transient events. It is understood that modifications to the invention may be made as might occur to one with skill in the field of the invention, within the scope of the appended claims. All embodiments contemplated hereunder that achieve the objects of the invention have therefore not been shown in complete detail. Other embodiments may be developed without departing from the spirit of the invention or from the scope of the appended claims.
Claims (2)
1. An electronic streak camera, comprising:
(a) a housing;
(b) a first objective lens disposed along an optical axis within an opening in a wall of said housing for forming an image of optical radiation passing along said optical axis from an emissive body;
(c) a pinhole field stop disposed along said optical axis at the focal point of said objective lens;
(d) a second collimating lens disposed along said optical axis for collimating radiation passing said pinhole field stop;
(c) a prism for splitting said radiation from said collimating lens into a characteristic optical spectrum of said radiation; and
(e) a third imaging lens for forming an image of said radiation from said prism;
(f) a detector array disposed at the focal plane of said third imaging lens for detecting said characteristic spectrum of said radiation.
2. The electronic streak camera of claim 1 wherein said detector array is a CCD array.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/148,910 USH1979H1 (en) | 1998-08-31 | 1998-08-31 | Electronic streak camera |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/148,910 USH1979H1 (en) | 1998-08-31 | 1998-08-31 | Electronic streak camera |
Publications (1)
Publication Number | Publication Date |
---|---|
USH1979H1 true USH1979H1 (en) | 2001-08-07 |
Family
ID=22527984
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/148,910 Abandoned USH1979H1 (en) | 1998-08-31 | 1998-08-31 | Electronic streak camera |
Country Status (1)
Country | Link |
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US (1) | USH1979H1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140367558A1 (en) * | 2013-06-18 | 2014-12-18 | Massachusetts Institute Of Technology | Methods and Apparatus for High Speed Camera |
US20200278302A1 (en) * | 2017-10-11 | 2020-09-03 | Krones Ag | Apparatus for inspecting containers, in particular cans |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4769552A (en) | 1986-01-24 | 1988-09-06 | Thomson-Csf | System for high speed reading of a charge transfer matrix optical sensor organized with one stroke frame transfer for the video detection of brief images |
US5101100A (en) | 1989-12-01 | 1992-03-31 | Hamamatsu Photonics K.K. | Streak camera operable with low deflection voltage |
US5144374A (en) | 1990-04-27 | 1992-09-01 | Cselt - Centro Studi E Laboratori Telecommunicazioni S.P.A. | Optical spectroscopy system |
US5221836A (en) | 1990-09-07 | 1993-06-22 | Hamamatsu Photonics K.K. | Streak tube having an arrangement for suppressing travel time spread of photoelectrons |
US5278403A (en) | 1991-04-29 | 1994-01-11 | Alfano Robert R | Femtosecond streak camera |
US5394237A (en) * | 1992-11-10 | 1995-02-28 | Geophysical & Enviromental Research Corp. | Portable multiband imaging spectrometer |
US5424827A (en) * | 1993-04-30 | 1995-06-13 | Litton Systems, Inc. | Optical system and method for eliminating overlap of diffraction spectra |
US5504575A (en) * | 1991-12-20 | 1996-04-02 | Texas Instruments Incorporated | SLM spectrometer |
US5636050A (en) * | 1994-02-15 | 1997-06-03 | Research Foundation Of City College Of New York | Apparatus using optical deflection |
-
1998
- 1998-08-31 US US09/148,910 patent/USH1979H1/en not_active Abandoned
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4769552A (en) | 1986-01-24 | 1988-09-06 | Thomson-Csf | System for high speed reading of a charge transfer matrix optical sensor organized with one stroke frame transfer for the video detection of brief images |
US5101100A (en) | 1989-12-01 | 1992-03-31 | Hamamatsu Photonics K.K. | Streak camera operable with low deflection voltage |
US5144374A (en) | 1990-04-27 | 1992-09-01 | Cselt - Centro Studi E Laboratori Telecommunicazioni S.P.A. | Optical spectroscopy system |
US5221836A (en) | 1990-09-07 | 1993-06-22 | Hamamatsu Photonics K.K. | Streak tube having an arrangement for suppressing travel time spread of photoelectrons |
US5278403A (en) | 1991-04-29 | 1994-01-11 | Alfano Robert R | Femtosecond streak camera |
US5504575A (en) * | 1991-12-20 | 1996-04-02 | Texas Instruments Incorporated | SLM spectrometer |
US5394237A (en) * | 1992-11-10 | 1995-02-28 | Geophysical & Enviromental Research Corp. | Portable multiband imaging spectrometer |
US5424827A (en) * | 1993-04-30 | 1995-06-13 | Litton Systems, Inc. | Optical system and method for eliminating overlap of diffraction spectra |
US5636050A (en) * | 1994-02-15 | 1997-06-03 | Research Foundation Of City College Of New York | Apparatus using optical deflection |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20140367558A1 (en) * | 2013-06-18 | 2014-12-18 | Massachusetts Institute Of Technology | Methods and Apparatus for High Speed Camera |
US9451177B2 (en) * | 2013-06-18 | 2016-09-20 | Massachusetts Institute Of Technology | Methods and apparatus for high speed camera |
US20200278302A1 (en) * | 2017-10-11 | 2020-09-03 | Krones Ag | Apparatus for inspecting containers, in particular cans |
US11614411B2 (en) * | 2017-10-11 | 2023-03-28 | Krones Ag | Apparatus for inspecting containers, in particular cans |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: UNITED STATES AIR FORCE, OHIO Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HOPKINS, MARK F.;REEL/FRAME:009477/0762 Effective date: 19980820 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |